Various known arrangements for transmitting uplink data packets from a mobile terminal to a network core will now briefly be discussed.
PDP contexts (QoS Flows) for both 2G and 3G are categorised into two groups, those which are guaranteed and those which are best-effort. The guaranteed PDP contexts have an associated guaranteed bit rate (or data rate) quantity which the network needs to provide for the PDP Context, and all PDP contexts may have a maximum bit rate. Best Effort PDP contexts do not have an associated guaranteed bit rate quantity. Normally when the guaranteed bit rate associated with a guaranteed PDP Context is not being met, the network will release the context.
In GPRS (2.5G) networks, the network schedules transmission of uplink data packets by a mobile terminal on a quality of service (QoS) flow by service flow basis. That is, the mobile terminal is allocated resources by the network to send uplink data packets for a specific service flow. In this case the additional downlink signalling load introduced by the scheduling of uplink data transmission from the mobile terminal for a specific service flow does not change the balance between signalling load and bandwidth of the system, as it is retrofitted to the design of GPRS and therefore the balance could not be changed. Its late introduction therefore had to rely upon using multiple scheduling identifiers, which theoretically limited the number of users with whom the resource can be shared, however it was felt not a significant problem in GPRS due to the limited bandwidth of the data channel associated with each scheduling channel and therefore normally the resource would have anyway been allocated to a single user to provide sufficient network quality.
When designing a scheduling channel for scheduling the transmission of uplink data packets from a mobile terminal to a network, it is important to be resource efficient, so that the maximum available bandwidth can be used for transmitting data.
In the enhanced data channel (E-DCH) of UTRAN (3G), the network schedules uplink packets sent by the mobile terminal with a single scheduling grant for the mobile terminal. This is possible either by using a primary or a secondary enhanced radio network temporary identifier (E-RNTI), which are used to signal to a single mobile terminal (primary E-RNTI) or a group of mobile terminals (secondary E-RNTI) the granted resources or a combination of both of them. The mobile terminal has a list of QoS flows (logical channels or queues) configured by the network and their associated priority. The mobile terminal shall consider the scheduling grant received by the network to be shared among all the configured QoS flows. With E-DCH a single granted rate is shared across the different queues. The mobile terminal fills the uplink transport block by emptying the queue of each QoS flow according to their priority. A problem with known arrangements of handling guaranteed and peak bit rates for QoS flows arises when the network is congested or when the radio conditions do not allow the exploiting of the maximum configured bit rate. In the congested network or when the radio conditions are not good enough, the resources allocated to a mobile terminal may be restricted. This restriction is applied either by the network by means of a lower scheduling grant assigned or by the same mobile terminal when, due to poor radio condition, mobile terminal transmitter power limitations apply and then the overall transmitter rate shall be scaled down accordingly. If the mobile terminal is configured with multiple QoS flows, and the highest priority flow has a guaranteed bit rate, and a peak bit rate higher than the guaranteed bit rate, this can cause resource starvation for the guaranteed bit rates for lower priority QoS flows. That is, the resources available to transmit uplink data for a particular mobile terminal may be such that, after transmission of the highest priority QoS flow, there is insufficient bandwidth available to transmit lower priority but “guaranteed” QoS flows for that mobile terminal.
This issue also occurs when operating two best-effort QoS flows in parallel: the resource used by the higher priority flow can grow to fill the whole grant allocated to the mobile terminal.
In the know arrangements discussed above all the data in a higher priority queue, up to the maximum or peak bit rate, are transmitted before data from a lower priority queue are transmitted. In the known arrangements the guaranteed bit rate is used by the network to allocate resources and may also be used to trigger release of a queue PDP context when the guaranteed bit rate is not being met.
Accordingly, it would be desirable to provide improved handling of queues of data for a mobile terminal with a telecommunications network.